Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2003
Publication Date: 5/25/2004
Citation: Schneider, M.J., Donoghue, D.J. 2004. Comparison of a bioassay and a liquid chromatography - fluorescence-mass spectrometry(n) method for the detection of incurred enrofloxacin residues in chicken tissues. Poultry Science. p. 830-834. 2004. Interpretive Summary: Enrofloxacin (ENRO) is a fluoroquinolone antibiotic approved for use in chickens in the U.S., due to its efficacy in treating a range of bacterial infections. Use of fluoroquinolone antibiotics in animals produced for food has raised concern as fluoroquinolone residues may lead to increased microbial resistance in humans. Efficient screening methods to monitor levels of ENRO residues in chicken muscle samples are thus needed. Here we evaluate a simple, inexpensive bioassay to determine if it can detect ENRO residues in incurred chicken muscle comparable to a more extensive liquid chromatography-fluorescence-mass spectrometry(n) method. Both methods were able to detect ENRO in incurred samples over a range of ENRO concentrations, from below tolerance, to near tolerance, to above tolerance. All samples determined to be above tolerance levels by the instrumental method were similarly determined to be above tolerance by the bioassay, illustrating the utility of the bioassay as a screening method. The ease of use of the bioassay and its low cost should facilitate its use as a screening method by regulatory agencies such as FSIS.
Technical Abstract: Regulatory monitoring for most antibiotic residues in edible poultry tissues is often accomplished with accurate, although expensive and technically demanding chemical analytical techniques. The purpose of this study is to determine if a simple, inexpensive bioassay could detect fluoroquinolone residues in chicken tissues above the FDA established tolerance (300 ppb) comparable to a liquid chromatography-fluorescence-mass spectrometryn method. To produce incurred enrofloxacin tissues for the method comparison, 40 d broilers were orally dosed in the water for three days at the FDA approved dose of enrofloxacin (50 ppm). At the end of each day of the 3 d dosing period and for 5 d post-dosing, birds were sacrificed and breast and thigh tissue collected and analyzed. Both methods were able to detect enrofloxacin at and below the tolerance level in the tissues, with limits of detection of 26 ppb (bioassay) and 0.1 ppb for enrofloxacin and 0.5 ppb for the enrofloxacin metabolite ciprofloxacin (liquid chromatography-fluorescence-mass spectrometry(n)). All samples which had violative levels of antibiotic were detected by the bioassay. These results support the use of this bioassay as a screening method for examining large numbers of samples for regulatory monitoring. Positive samples should then be examined by a more extensive method, such as liquid chromatography-fluorescence-mass spectrometryn , to provide confirmation of the analytes.